Delta-shaped aircraft are characterized by highly swept-back wings and a relatively low aspect ratio which results in a generally triangular planform. While conventionally shaped aircraft are defined by a central fuselage with laterally protruding wings, delta-shaped aircraft have an integrated fuselage and wing configuration. In this respect, typically the modern "stealthy" type of delta-shaped aircraft have an aerodynamic lifting surface which is defined by a central fuselage which smoothly blends with highly swept-back wings. In fact, because of this smooth integration, these aircraft are contemplated as having only a single wing and these aircraft are sometimes referred as being a "flying wing." Some present examples of delta-shaped aircraft include the U.S. military's B-2 bomber and the F-117 stealth fighter.
Due to the increased aerodynamic lifting surface area of these aircraft in comparison to conventional aircraft, delta-shaped aircraft are aerodynamically highly efficient. In addition, these aircraft are designed to have relatively long straight leading edges, albeit swept-back, when viewed topwise or bottomwise. The surface contours, however, are specifically formed to follow smooth continuous curves and having no or few acute angulations, especially right angles. Such surface contouring is contemplated to result in a relatively low overall aircraft radar signature, and thus making delta-shaped aircraft "stealthy."
As one of ordinary skill in the art will appreciate, aircraft must reduce their speed when performing landing operations. To perform this function, conventional aircraft typically employ flaps which are ratably attached to the trailing edges of the wings. The flaps are deflected downward, and in some configurations the flaps are also extended aftward, in order to produce drag, thereby slowing down the aircraft to required landing flight speeds.
Modern stealthy delta-aircraft, however, do not have traditional flaps at the trailing edges of the wings. For example, in the case of the B-2 stealth bomber, the aircraft does not even have downwardly deflectable or aftward extendable flaps for producing drag and slowing the aircraft. These aircraft typically have angled elevons and rudders for their control surfaces which are mounted to the trailing edge of the wing. Among other design constraints, this is due to radar signature mitigation reasons. As such, in addition to reducing engine power, these aircraft reduce their speed for landing operations by approaching the landing area at a relatively high angle-of-attack or nose-up in order to increase drag.
Operating an aircraft at a high angle-of-attack has several implications. Increasing the angle-of-attack with respect to the forward direction of flight tends to increase the lift. Regardless of any increase in the lift due to angle-of-attack effects, as the speed of the aircraft is decreased, at some point additional lift may be required to maintain the desired altitude and possibly prevent a stall condition. As such, several sets of control surfaces called elevons are disposed at the trailing edges of the delta wing. Elevons are angularly disposed with respect to the longitudinal axis or centerline of the fuselage within the horizontal plane. The elevons function much the same as ailerons and elevators for respectively turning and pitching conventional aircraft. Reliance upon the use of elevons or other aerodynamic control surfaces, however, undesirably increases the radar observable signature of the aircraft. Further, use of such aerodynamic control surfaces may necessitate the use of auxiliary control surfaces, such as trim tabs which further tend to increase radar signature.
In addition to increasing the aircraft radar signature and reliance upon control surfaces, operating the aircraft at a high angle-of-attack results in the pilot having poor over the nose visibility or at least obstructed visibility in the forward direction. This is due to the projecting nose of the fuselage obstructing the pilot's forward view and/or downward view of the landing surface. As one of ordinary skill in the art can appreciate, pilot visibility is of an utmost safety concern. For example, nighttime landing operations aboard an aircraft carrier are a potential dangerous undertaking and decreased pilot visibility greatly increases the risk of harm.
As such, based upon the foregoing, there exists a need in the art for an improved method and device, for use with delta-shaped aircraft, which mitigates the aircraft radar signature, reduces the reliance upon control surfaces, and improves aerodynamic lift and pilot visibility in comparison to the prior art.